Something similar happened with this print as well. The quality was greatly reduced when it got down to the tip. I personally didn't zero everything so it could have been much more precise. We also have a replicator that can do 80 microns so I will be seeing about that before too long.

I tried buffing one of this, but that really didn't work out. I think the buffer was spinning too fast (fixed speed). I did some minimal grinding but the finish itself came out alright. Of course the lines are there.